Progressive ophthalmic lenses allow sharp vision of objects which are located at varying distances in front of the lens wearer, the wearer being presbyopic. For this purpose, each progressive ophthalmic lens has a mean refractive power which varies along a meridian line of the lens. Here, the meridian line corresponds to the main gaze direction used by the wearer to see at varying distances. The vision distances may be defined by using an ergorama. As a general rule, the vision distance decreases from more than 2 meters for a far vision gaze direction, to about 40 centimeters for a proximate vision gaze direction which is oriented below the far vision gaze direction.
But out of the meridian line, a progressive ophthalmic lens has mean refractive power values and resultant astigmatism values which are not equal to those on the meridian line at constant height for a same gaze direction lowering angle. As a consequence, the optical powers which are actually produced by each lens do not match exactly the prescription out of the meridian line and out of lens zones dedicated respectively to far vision and proximate vision. Many efforts have been spent for years to increase the far- and/or proximate vision areas in combination with reducing the correction deviations out of these areas and the meridian line. But these improvements relate in optimizing each lens separately.
In addition, it has been discovered that the wearer's binocular vision can be improved by selecting appropriately both lenses which pertain to one and same pair, each with a different lens design. For example, document FR 2 704 327 proposes selecting one of the ophthalmic progressive lenses of the pair with a large far vision zone, and the other ophthalmic progressive lens of the pair with a large proximate vision zone. As a consequence, the lens with large far vision zone has a reduced proximate vision zone, and the one with large proximate vision zone has a reduced far vision zone. But binocular vision allows the wearer to select the one of his eyes which has sharper vision for each binocular gaze direction. Thus, each of the largest far- and proximate vision zones between both lenses appears to be actually effective for providing sharp binocular vision, whereas the smallest far- and proximate vision zones are useful for providing stereoscopic vision perception.
U.S. Pat. No. 7,083,277 discloses another example of lens pair with both lenses being different in far- and proximate vision field widths.
However, vision discomfort may still arise when both lenses of the pair are thus selected with different designs. In particular, such discomfort relates to peripheral gaze directions with respect to the meridian lines of the lenses.
Starting from this situation, an object of the present invention consists in improving binocular vision of a wearer of ophthalmic progressive lenses, while avoiding discomfort for peripheral vision.